In aircraft and other vehicles various display devices are provided for displaying images and information. Some of these devices also include input means for inputting information to the device. In the case of aircraft, for example, such devices may be utilized for various different purposes. For example, they may be flat panel screen devices provided as parts of the in-flight entertainment system for displaying movies and information to passengers, or flight attendant panels, which may comprise a touch screen as input means and which are mounted in the aircraft cabin such that they are accessible to the flight attendants. The flight attendants panels are adapted for displaying status information to the flight attendants and for allowing the flight attendants to enter control commands for controlling various on-board equipment, such as the flight entertainment system, the air conditioning system, the lighting system and the audio system.
Whether or not such display devices include a touch screen, they also necessarily comprise hardware switches, e.g. for actuation of important functions, such as an emergency function. They are typically disposed below the display screen of the display device, and may be provided as individual switches or as groups of switches, e.g. constituting a keypad or keyboard. In the case of touch screen devices, hardware switches, which may take the form of, for example, pushbuttons or keys, provide the advantage that they are also operable if the touch screen is no longer functional and can always be actuated without having to at first switch between different screens of a user interface implemented on the touch screen.
These hardware switches occupy a substantial space in the display device, so that their use and arrangement must be carefully chosen. Further, it may be desired to provide different hardware switches—or groups of hardware switches—for different applications, in order to customize the display device for a particular use scenario.
Similar considerations also apply to communication hardware enabling the display device to communicate via wired or wireless transmission paths.
In any case, this necessitates keeping available different hardware components and wiring selected ones of these to electrical circuitry inside the display device. In this connection it must also be taken into consideration that for some security relevant functions, such as, e.g., an emergency function, regulations require the corresponding electrical circuitry inside the display device being segregated in hardware from electrical circuitry associated with other functions, and that any change of constructive features of the display device may require new certification or testing. In particular, it may be required that each configuration of a display device must be tested separately and is assigned a separate part or certification number.